March 10, 2011

Infrared Cameras Reveal The Science Behind Kangaroo Hops

by ssavage

A team of researchers from the Royal Veterinary College in London, the University of Idaho, the University of Queensland, and the University of Western Australia are attempting to uncover the precise details of how kangaroos bounce.

"The team is interested in trying to understand how the group of kangaroos change their body posture and hopping mechanics with body size," explained Craig McGowan of the University of Idaho.

Researchers were loaned a novel motion capture system from the firm Vicon that is capable of "looking past" that focuses on their study subjects, BBC News reports.

Most animals adopt a more upright posture as their body mass increases, redistributing their weight to allow more efficient movement. Kangaroos, however, do not appear to adjust their posture in this way.

Motion-capture records movement, registering and analyzing reflections from small plastic markers stuck on to the moving entities, similarly to how golf coaches use it to analyze students' swings. It is the same technology used in the Lord of the Rings films to translate the movements of actor Andy Serkis into those of the creature Gollum.

The researchers measure the forces that the kangaroos' feet exert on the ground - and thus that are transmitted through their legs - using what are known as force plates. "That reduces the mechanical demands on the musculature - so it increases their 'mechanical advantage'."

The team also captured the kangaroos' movement using the traditional method of high-speed video - which in the past was analyzed frame-by-frame to obtain the same kind of data that the motion-capture system provides automatically.

The experiments were conducted in Alma Park Zoo in Brisbane and have rendered a large amount of useful data that the team will study for quite some time. But Dr. Alexis Wiktorowicz-Conroy said the outcome was certain to solve some of the biomechanical mysteries of the roo.

"We want to know how are they able to hop fast - even when they are quite heavy - and not change posture," she told BBC News. "That's important, because these animals get really big, and we can't really explain without this why their bones don't break at high speeds."

"People have started to look at that in ankle joints; we're looking more at joints in hind limbs. There's a lot we don't know about them, and this is going to help study questions about hopping and animal locomotion in general."

"We hope in the end we can use this in veterinary medicine and for conservation," Conroy concluded.